Chapter 9:
Cellular Respiration
& Fermentation
ATP & Energy
I. Structure of ATP
A. ATP (Adenosine Triphosphate) – shuttles energy
for cells
B. ATP is composed of ribose (a sugar), adenine (a
nitrogenous base), and three phosphate groups
II. ATP & Energy
A. The bond between the terminal phosphate
groups of ATP’s can be broken, releasing organic
phosphate and leaving ADP (adenosine
diphosphate).
B. Energy is released from ATP when the terminal
phosphate bond is broken.
C. This release of energy comes from the chemical
change to a state of lower free energy
(stabilizing), not from the phosphate bonds
themselves.
Glycolysis & Fermentation
I. Harvesting Chemical Energy
A. Cellular Respiration – the break down of
organic compounds (food, glucose, etc.) in
cells to make energy, ATP molecules
C6H12O6 + 6O2  6CO2 + 6H2O + Energy
B. Glycolsysis
1. Biochemical pathway that always starts
cellular respiration!!!
2. Does produce a small amount of ATP.
3. Other products can follow two other
pathways, depending on whether oxygen is
present not.
ATP
Glycolysis
Oxygen Absent
Fermentation
(anaerobic)
Oxygen Present
Aerobic
Respiration
ATP
C. Two (2) Types of Cellular Respiration
1. Anaerobic Respiration – respiration without
oxygen
– Also called fermentation
2. Aerobic Respiration – respiration with oxygen
II. Glycolysis
A. Basics of Glycolysis
1.
glyco: sugar
lysis: break up
• Begins to break down glucose & releases a small
amount of energy (ATP)
2. Occurs in the cytoplasm.
3. All types of cellular respiration begin with
glycolysis!!!!!!!!!!
B. Major events in Glycolysis
1. Start with (invest) 1 glucose, 2 NAD+, and 2 ATP
molecules.
2. Glucose, a 6-carbon molecule, is split into 2 PGAL,
or glyceraldehyde-3-phosphate, molecules (each a
3-carbon molecule).
3. Hydrogens are transferred from the 2 PGAL
molecules to the 2 NAD+ molecules. This produces
2 NADH molecules.
4. 4 ATP molecules are then produced (2 ATP overall).
This also produces 2 pyruvic acid molecules.
5. Ends with 2 pyruvic acid, 2 ATP, 2 NADH molecules.
Glycolysis
III. Anaerobic Respiration
A. Basics
1. Also known as Fermentation
2. Does not make any ATP!
3. Does remake NAD+, which goes back through
Glycolysis to make 2 more ATP.
B. 2 Types of Fermentation
1. Lactic Acid Fermentation
• 2 H+ are removed from 2 NADH to make NAD+.
• Pyruvic acid is converted into lactic acid by
gaining the 2 H+.
• NAD+ goes back through glycolysis to make
more ATP.
Figure 9.17b
2 ADP  2 P i
Glucose
2 ATP
Glycolysis
2 NAD 
2 NADH
 2 H
2 Pyruvate
2 Lactate
(b) Lactic acid fermentation
2. Alcoholic Fermentation
• A CO2 molecule is removed from each pyruvic
acid, creating acetaldehyde.
• 2 H+ are removed from 2 NADH to make NAD+.
• Acetaldehyde is converted into ethyl alcohol
by gaining the 2 H+.
• NAD+ goes back through glycolysis to make
more ATP.
Figure 9.17a
2 ADP  2 P i
Glucose
2 ATP
Glycolysis
2 Pyruvate
2 NAD 
2 Ethanol
(a) Alcohol fermentation
2 NADH
 2 H
2 CO2
2 Acetaldehyde
IV. Mitochondria Review
A. Structure
1. Surrounded by a double membrane
2. The 2nd, inner membrane, is highly folded to
increase surface area. Each fold is called a
cristae
3. The very interior of the mitochondria is called
the mitochondrial matrix.
IV. Aerobic Respiration
A. Basics
1. Aerobic Respiration requires oxygen (O2)!
2. Produces nearly 20 times more ATP than
glycolysis alone.
3. Begins with Glycolysis, followed by the Kreb’s
Cycle, the Electron Transport Chain, and
Chemiosmosis.
B. Glycolysis
1. Converts glucose into 2 pyruvic acids.
2. Makes 2 NADH and a net of 2 ATP.
3. Occurs in the cytoplasm
C. Pyruvic acid is converted into Acetyl CoA.
1. The 2 Pyruvic Acids pass through both
mitochondrial membranes into the
mitochondrial matrix.
2. As this happens, the 2 pyruvic acids reacts with a
molecule called coenzyme A to form Acetyl CoA.
3. 2 NADH’s and CO2 are produced.
D. Kreb’s Cycle
1. Each Acetyl CoA is broken down to make 1 ATP, 3
NADH, and 1 FADH2.
2. 1st product is remade in the last step, so the
Kreb’s Cycle can happen again.
3. Remember, there are 2 Acetyl CoA’s, so the
Kreb’s cycle will happen twice.
4. Our totals are therefore: 2 ATP, 6 NADH, and 2
FADH2.
Acetyl CoA
CoA-SH
NADH
+ H
H2O
1
NAD
8
Oxaloacetate
2
Malate
Citrate
Isocitrate
NAD
Citric
acid
cycle
7
H2O
Fumarate
NADH
3
+ H
CO2
CoA-SH
-Ketoglutarate
4
6
CoA-SH
5
FADH2
NAD
FAD
Succinate
GTP GDP
ADP
ATP
Pi
Succinyl
CoA
NADH
+ H
CO2
E. Electron Transport Chain
1. Occurs across the inner membrane of the
mitochondria (cristae).
2. H+ ions are released from NADH and FADH2 into
the mitochondrial matrix.
3. The electrons in the hydrogen atoms are at a
high energy level!
4. The high energy electrons are passed along a
series of molecules called the Electron Transport
Chain.
E. Electron Transport Chain (cont.)
5. As the electrons move from molecule to
molecule, they lose some of their energy.
6. This energy pumps H+ out of the mitochondrial
matrix, into the space between the two
mitochondrial membranes.
7. A high concentration of H+ builds up in this
space.
Electron Transport Chain
F. Chemiosmosis
1. H+ ions diffuse from the high area of
concentration made in between the 2
mitochondrial membranes to the low are in the
matrix.
2. Specifically the H+ ions move through a protein
called ATP Synthase.
3. As H+ ions move through ATP Synthase, ATP is
made!
4. 34 ATP are made in chemiosmosis.
5. The H+ ions then combine with oxygen to form
water.
Electron Transport Chain
Summary of Aerobic Respiration
Total ATP made aerobically: 38 ATP’s
Glycolysis = 2
Kreb’s Cycle = 2
Electron Transport Chain = 34